1. Field of the Invention
The present invention relates to wireless communications systems and, more particularly, to quality of service in 3G wireless communications systems such as cdma2000.
2. Description of Related Art
In the existing art, there are at least three basic packet data services that call for associated levels of quality of service (QoS). These three services are (i) normal web activity, such as FTP, HTTP and e-mail services, (ii) streaming media, such as streaming audio and video, and web casting, and (iii) real-time two-way conversational grade service.
Normal web activity, such as file transfers, e-mail access and general web browsing can operate with a low quality of service. For such services, a simple “best effort” service level is therefore acceptable.
Non-real time media transfers (e.g., broadcasts of audio or video, such as radio broadcasts for instance) over a packet-switched network may require a higher level of service quality. Such services are largely unidirectional, with a host sending data (e.g., packetized media) to a client, and the client sending only a relatively small quantity of acknowledgement data back to the host. In some cases, the client terminal might provide a buffer for the incoming media, so that the user will actually hear/see the media with a brief delay, such as a second or more. This type of service can tolerate variations in delay and data loss, but it may require more bandwidth than simple file transfers or the like.
Real-time media transmissions over a packet-switched network, such as audio conferencing (e.g., voice over IP) or video conferencing (packet video services) for instance, have little tolerance for delay and for transmission errors (such as packet or data loss). Such services generally call for a premium level of service quality.
For any communication in a telecommunications network from one endpoint to another (end-to-end, or E2E), a desired level of QoS can be provided only if all portions of the communications path from end-to-end can be set up to support at least that desired level of QoS. If any portion of the communications path does not support at least the desired level of QoS, that portion will serve to restrict the end-to-end QoS.
3G wireless telecommunications networks, such as cdma2000 networks, raise a new issue in this regard.
Generally, in a wireless telecommunications network, an area is divided geographically into a number of cell sites. Each cell site is defined by a radio frequency (RF) air interface from a base transceiver station (BTS) antenna. The BTS antenna is then coupled to a base station controller (BSC), which controls communications over the air interface, such as by dictating power levels and other parameters. (Together, the BTS and BSC may therefore be considered to define a “base station system” or simply a “base station.”) In turn, the BSC is coupled with a switch or gateway, which provides connectivity with a transport network such as the public switched telephone network (PSTN) or the Internet. A mobile station operating in the cell site can then communicate with a node on the transport network, via a communication path including the air interface, the base station, the gateway and the transport network.
In a 3G wireless telecommunications network, a packetized communication path is provided between a mobile station and the transport network, as illustrated by way of example in FIG. 1. In this arrangement, a mobile station 12 communicates over an air interface 14 with a BTS 16 and in turn with a BSC 18 (the BTS 16 and BSC 18 cooperatively defining a base station 20). BSC 18 is then coupled by an industry standard A10/A11 link to a packet data serving node (PDSN) 22, which, as a network access server, provides connectivity with a packet-switched network 24 such as the Internet. A remote node 26 may in turn sit on or be accessible via the packet-switched network.
The mobile station may take various forms. For instance, it can be cellular or PCS telephone, or it can be a notebook computer or personal digital assistant (PDA) that includes or is connected with a cellular or PCS telephone or with a wireless communications card. Other examples are possible as well.
As further shown in FIG. 1, end-to-end communication may be established from the mobile station 12 to the remote node 26 over a packetized communication path made up of three segments: (A) the air interface 14 between the mobile station and the base station, (B) the A10 link between the base station and the PDSN, and (C) the packet-switched network 24 between the PDSN and the remote node. Thus, a packet sequence representing a communication from the mobile station passes through these three segments to the remote node, and a packet sequence representing a communication from the remote node passes through these three segments to the mobile station.
To provide a designated level of QoS for communications between the mobile station and remote node, all portions of the communication path between the mobile station and the remote node should support at least the designated level of QoS. In the existing art, methods are known for helping to set up and provide a designated level of QoS over the first and third of these parts, the air-interface and the packet-switched network. Further, the segment between the base station and the PDSN can be assumed to provide a sufficient grade of service for all users without requiring any QoS management.
However, the present inventors have discovered that what is missing is some method for consistently linking the levels of QoS established in the first and third segments, so as to help provide a complete end-to-end QoS solution.